1. Field of the Invention
The present invention relates to a wet image forming apparatus for developing an electrostatic latent image by using liquid developers of a plurality of colors to thereby form a color image.
2. Description of Related Art
In electrophotographic image forming apparatuses, it is predominant practice to transfer an electrostatic latent image formed on a photosensitive drum by using a powdery developer. An image forming apparatus has been recently proposed which forms an image through development by using a liquid developer in which toner particles are dispersed in a carrier liquid. Known as such a wet image forming apparatus is, for example, an image forming apparatus as disclosed in patent document 1 which forms color images by using liquid developers of mutually different colors, for example, black, magenta, cyan, and yellow, and then sequentially transfers these color images to thereby form a full-color image.
It is known that, as disclosed in patent document 2 for example, for liquid developers of a wet image forming apparatus as described above, only a carrier liquid is extracted by using a carrier recycling device from the used liquid developer and then recycled.
[Patent Document 1] JP-A-No. 2005-315948
[Patent Document 2] JP-A-No. 2005-77896
In a wet image forming apparatus as described above, a liquid developer whose concentration is controlled to a desired level by mixing a carrier liquid with a condensed liquid developer or the like is supplied to a photosensitive drum. At this point of time, it is possible, as disclosed in patent document 2, to use carrier liquids to be recycled as the carrier liquids used for the concentration control.
When the carrier liquid to be recycled is used, it is preferable that the carrier liquids be extracted from the used liquid developers of different colors (for example, black, cyan, magenta, and yellow) all at a time in order to increase the amount of carrier liquid extracted. That is, the liquid developers of the different colors are once mixed together and then the carrier liquid to be recycled is extracted from the mixed liquid developer.
However, a carrier liquid extracting device usually used has difficulties in completely removing toner particles from the used liquid developers of the different colors, thus leaving the toner particles, although small in amount, in the extracted carrier liquid. The use of such carrier liquid extracted from the mixed liquid developers possibly results in a phenomenon that the toner particles of the other colors appear outstanding in, for example, the yellow liquid developer. This therefore involves a problem that color reproducibility becomes unstable at the time of image formation.